This report reviews the key issues raised during a three-day workshop jointly organised, in November 2015, by the Stockton Centre for the Study of International Law at the U.S Naval War College and the Centre for the Rule of Law at the U.S Military Academy. This event gathered academics, representatives from the UN, the ICRC, non-governmental organizations and States - the United Kingdom, the Netherlands, Canada and the United States (including many members of the US government).

After presenting the geopolitical history of the region and the background to the conflicts in Syrian, the report enunciates various legal issues that will be discussed. Several issues related to the use of force were considered: from the support given to Syrian rebel groups, to the Syrian government, as well as actions taken against ISIS. For instance the question of whether US programs supporting rebels could trigger the armed attack threshold, was raised. A number of participants agreed that US support had not triggered Syria's right to self defence, since they consider that there exists a gap between the article 2(4) and the article 51 of the UN Charter. Moreover the concept of 'unable and unwilling' as a grounds for justifying the use of force was examined. Then the discussion turned to the US actions against al-Nusra Front.

Secondly, the classification of the conflict was questioned. Many agreed that there exist three broad categories of NIACs: those between various opposition groups and the Syrian government and Russia (1), those between various States and ISIS (2), those between opposition groups fighting among themselves (3). Some participants argued that there is an additional one between Turkey and the Syrian Kurds, and another one between the US and al-Nusra. One participant believes that there was a brief IAC between Turkey and Russia. Then the date of emergence of a NIAC and so the intensity criterion established in Tadić, was discussed, as well as the geographical applicability of Common Article 3 and the customary law of armed conflict in a NIAC. The participants did not agree on this point. Later the issues of arming, training and employing proxies were analysed.

Thirdly the legal implications arising from the presence of foreign fighters, as well as various States' approaches to the implementation of the SC resolutions 2179 and 2178 were studied. Considering the law governing the conduct of hostilities in Syria, the prominence of customary law was highlighted as well as the applicability of Common article 3. Three different visions on the use of human shields emerged: all human shields should be protected as civilians (1), voluntary human shields are considered as directly participating in the hostilities and therefore lose their protected status (2), while they are not directly targetable they could be disregarded in the proportionality calculation (3).

Finally the group addressed various accountability mechanisms for war crimes in Syria, including the ICC, with special regards to the question of its jurisdiction over the use of chemical weapons as a standalone crime, domestic prosecutions and ad-hoc international hybrid tribunals.

Unfortunately the workshop did not result in a solution, or even consensus. The report ended on another question, regarded as the most important one, that echoes the title: Can international law effectively regulate such conflict.